1. Field of the Invention
The present invention relates to a method for making a stabilized color filter. The stabilized color filter can be used to capture or display an image in color and can be used for image capture in a color digital camera when employed in combination with a charge coupled device (CCD). More particularly, the present invention relates to a stabilized color filter, and its stepwise fabrication. The stabilized color filter comprises an electroactive substrate, such as a silicon substrate, and dye loaded phenolic resist layers which respectively are capable of filtering light to provide light having a first predetermined wave length, light having a second predetermined wave length, and light having a third predetermined wave length. In addition, where at least one of the dye loaded phenolic resist layers is a cross-linked silylated phenolic resist layer which has been found to provide enhanced resistance to interlayer penetration.
2. Description of the Prior Art
Digital cameras having color capability have been developed which employ a charge couple device (CCD), and a multilayered silicon chip containing photosensitive elements, as the film; the CCD transforms light into electrical charges which can then be digitized by the camera's electronics. A color filter can be used in combination with the CCD. The color filter can be used to capture an image by separating the transmitted, or reflected light, into its component colors and storing them in adjoining pixels on an electroactive silicon substrate. Transfer of the image is achieved by transforming light into electrical charges which are moved out of the array by the CCD and digitized by the camera's electronics.
During the fabrication of the color filter, resists can be applied in a stepwise manner onto a silicon wafer. For example, a photo resist containing a red dye component can be spun onto a silicon wafer and thereafter exposed, developed, and baked. Similarly, resists containing a blue dye and a green dye can be respectively applied to the silicon chip.
Experience has shown that unless proper procedures are utilized, intermixing of the dye loaded contiguous resist layers of the color filter can occur which can adversely impact their optical properties. One solution is to employ resists having certain organic solvents, for example diglyme, or cellosolve acetates, which have been found to substantially reduce or avoid inter-resist-layer overlap. However, use of such solvent's has been discontinued because they are classified as being "environmentally unsafe".
It would be desirable therefor to provide an environmentally safe method for making a multilayered color filter containing photosensitive elements which could be used as an image sensor, or in projection display applications.